Đáp án:
a, `x ≥ 4/3 => |3x - 4| = 3x - 4`
Ta có :
`P = 1 - 1/4 . (x : 1/10 - 15/4) - 2.|3x - 4|`
` = 1 - 1/4 . (10x - 15/4) - 2(3x - 4)`
` = 1 - 1/4 . ((40x - 15)/4) - (6x - 8)`
` = 1 - (40x - 15)/16 - 6x + 8`
` = 9 - ((40x - 15)/16 + (96x)/16)`
` = 9 - (40x - 15 + 96x)/16`
` = 9 - (136x - 15)/16`
` = 144/16 - (136x - 15)/16`
` = (144 - 136x - 15)/16`
` = (129 - 136x)/16`
b, `x < 4/3 => |3x - 4| = -(3x - 4) = 4 - 3x`
`=> P = 1 - 1/4 . (x : 1/10 - 15/4) - 2.|3x - 4|`
` = 1 - 1/4 . (10x - 15/4) - 2(4 - 3x)`
` = 1 - 1/4 . ((40x - 15)/4) - (8 - 6x)`
` = 1 - (40x - 15)/16 - 8 + 6x`
` = -7 + (96x)/16 - (40x - 15)/16`
` = -7 + (96x - 40x + 15)/16`
` = -7 + (56x + 15)/16`
` = -112/16 + (56x + 15)/16`
` = (-112 + 56x + 15)/16`
` = (56x - 97)/16`
Giải thích các bước giải:
